If there is gene flow between two adjacent populations of the same species, they will

A) have similar gene pools.
B) become genetically isolated from each other.
C) develop into different species.
D) experience directional selection.
E) merge into one population.

Gene flow means that individuals from one population can mate and reproduce with individuals from another population, which leads to the exchange of genetic material. As a result, the two populations will have similar gene pools as the gene flow evens out genetic differences between them. Choice B is incorrect as gene flow prevents genetic isolation. Choice C is incorrect as it takes a longer time and many more processes apart from gene flow to lead to the development of a new species. Choice D is incorrect as directional selection occurs when one phenotype is favored over others, leading to a shift in allele frequency, whereas gene flow is the movement of alleles between populations. Choice E is also incorrect as it suggests that gene flow will result in the formation of a larger population, as opposed to just making the two adjacent populations more similar in terms of allele frequency.